1. Field of the Invention
The present invention relates to a door lock, and more particularly to a door lock which can control an alarm apparatus to generate an alarm signal when a burglar pries open or damages the door lock.
2. The Prior Art
The commercially-available alarm system is generally turned on/off by a key switch. In some cases, the key switch is installed inside the house. When the occupier wants to leave the house, all the doors, except the front door, and windows must first be closed, and then the key switch be operated to turn on the alarm system. Within a time-delay period of, for example, 30 seconds after the system is turned on, the front door must be closed. In this circumstance, the user always feels a psychological pressure because of the limited time delay. Sometimes, after the alarm system is turned on, the user discovers that something has been forgotten in the house. He has to turn off the alarm system first, and then re-enter the house, or the alarm system will generate an undesired signal. In some cases, the key switch is installed on the outside wall beside the front door. Although this can prevent the above-described disadvantage, it still has several drawbacks. For example, the key switch is fairly easy to pick and destroy in order to shut off the alarm system, and thus cannot offer reasonable security. In both cases, the installation of the key switch is inconvenient, and will damage the wall decoration of the house. In addition, the user has to carry an additional key for the key switch.
Furthermore, the connecting wires of the alarm system are sometimes cut off by the skilled burglar to shut off the alarm system. In addition, since the alarm system is very expensive, it is not widely used.
At present, several door locks which cannot be picked by skeleton keys or other picklocks are commercially available. However, the burglars are still able easily to damage door locks in several ways to open doors. Therefore, such door locks also cannot offer reasonable security.